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Biomedical subjects

M Haddad

Publications and source records attributed to M Haddad.

At least 55 records · Page 3Linked to original sources
PubMed1998

Stanniocalcin in the seawater salmon: structure, function, and regulation.

Stanniocalcin (STC) is a homodimeric glycoprotein hormone that was first discovered in fish, where it is produced by unique endocrine glands known as the corpuscles of Stannius (CS). In freshwater salmon, STC plays an integral role in Ca2+ and phosphate homeostasis. High levels of extracellular Ca2+ promote the synthesis and release of STC, which on entering the bloodstream reduces the levels of gill and gut Ca2+ transport and renal phosphate excretion to restore normocalcemia. In this report, we have examined STC in seawater salmon. We have studied the distribution of STC protein and mRNA in marine Atlantic salmon CS cells, the responsiveness of these cells to Ca2+, and some physical properties of the hormone. Our results demonstrated that all Atlantic salmon CS cells expressed the STC gene. Furthermore, these cells exhibited a Ca2+ sensitivity that was remarkably similar to those in freshwater salmon in terms of its ability to stimulate STC secretion and gene expression. When Atlantic salmon glands were fractionated by concanavalin A (ConA)-Sepharose chromatography, two distinct forms of the hormone were identified, both of which were recognized by sockeye salmon STC antiserum, and designated as STC1 and STC2. STC1 was a glycosylated, 42-kDa disulfide-linked dimer, with a high affinity for ConA. STC2 did not bind to ConA, was 44 kDa in size, and had a different subunit structure. STC2 was also a less effective inhibitor of gill Ca2+ transport in fish. Collectively, the results suggest that there is a second form of STC in salmon.

Animals↗
PubMed1998

Retroperitoneal endoscopic lumbar sympathectomy with balloon dissection: experience with a cadaveric model.

The objective of this study was to determine the feasibility of retroperitoneal endoscopic lumbar sympathectomy with balloon dissection technique using a cadaveric model. Retroperitoneal endoscopic lumbar sympathectomy was performed on 10 cadavers. The procedure was combined with balloon dissection to provide easier visualization and more working space. The outcome was successful in eight cadavers. Average operating time was 40 min, and visualization was good. The only major technical problems were perforation of the peritoneum and air leak into the abdomen. It was concluded that retroperitoneal endoscopic lumbar sympathectomy with balloon dissection has the advantages of minimal invasiveness, clear visualization, and controlled blunt dissection. The use of a cadaveric model may improve the clinical learning curve.

Cadaver↗
PubMed1998

Combined surgical correction of bilateral congenital lower limb lymphedema with associated anomalies.

An unusual combination of congenital malformations in a 16-year-old emotionally disturbed man is described. The anomalies included severe congenital bilateral leg lymphedema, bilateral gynecomastia, unilateral cataract, and malformed external genitalia. Genetic and hormonal investigations were unremarkable. Multiple concomitant operations (vascular and plastic surgeons) to correct the deformities and restore physical well-being and self-esteem were undertaken.

Adolescent↗
PubMed1998

Laparoscopic cholecystectomy and appendectomy with sickle cell disease.

Thirty-six pediatric and adult patients with sickle cell disease (SCD), cholelithiasis, and repeated abdominal crises underwent laparoscopic cholecystectomy (LC) and appendectomy with minimal complications. We prefer using LC to the open method for patients with SCD, and we propose adjustments to the positions of the four trocars to facilitate both procedures without adversely affecting the patient.

Abdominal Pain↗
PubMed1998

Impact of reorientation algorithms on quantitative myocardial SPECT perfusion imaging.

UNLABELLED: In myocardial SPECT perfusion imaging, reorientation algorithms from transaxial image planes are used to generate short- and long-axis views of myocardial tracer uptake. We performed phantom experiments with 201Tl to delineate how image reorientation affects the results of quantitative image analysis. METHODS: Thirty consecutive patient studies were analyzed to characterize the distribution of the angle of reorientation in a clinical setting. Short-axis SPECT images of a cardiac phantom with and without a 180 degrees cold-spot insert were reconstructed with three different backprojection filters (ramp, Metz and Butterworth) and reoriented through different angles ranging from 45 degrees to 89 degrees. Four interpolation algorithms were used to calculate from the transaxial images the pixel values of the reoriented images: (a) a simple interpolator that averages the pixel values of the eight neighboring pixels of the transaxial image; (b) a three-dimensional linear interpolator; (c) a hybrid interpolator that combines a two-dimensional linear in-plane with a one-dimensional cubic across-plane interpolation; and (d) a three-dimensional cubic convolution interpolator. Images were reoriented twice with opposite angles so that the original and the reoriented images could be directly compared. Circumferential profile analysis was applied to determine the root mean square error of corresponding profiles and the difference of the extent and the severity of perfusion defects. Single and multivariate analyses of variance (ANOVA) were used to compare the effects of the reorientation angle, the backprojection filter and the interpolation algorithm. RESULTS: In the clinical studies, the angle between the transaxial and reoriented images was 75 degrees +/- 10 degrees (s.d.). In 48 phantom experiments, multivariate ANOVA demonstrated that the backprojection filter and the interpolation algorithm significantly affect the circumferential profiles and the extent and severity of a perfusion defect (p < 0.05). In contrast, the angle of reorientation was not a significant factor (p = ns). By univariate analysis, the three-dimensional cubic interpolator was associated with significantly (p < 0.05) less error than the simple and three-dimensional linear algorithms. Relative computation times (simple interpolator = 100%) were 119% for the three-dimensional linear, 136% for the hybrid and 243% for the three-dimensional cubic interpolator. CONCLUSION: For quantitative analysis of myocardial SPECT perfusion images, a Metz filter for filtered backprojection in combination with a three-dimensional cubic convolution interpolation for image reorientation appears to offer improved accuracy.

Algorithms↗
PubMed1997

[Traumatic common carotid-internal jugular fistula: positive aspect].

A 42-year-old man presented with a penetrating neck injury from a pellet gun. Physical examination showed an open 1 cm wound on the right side of the neck, hematoma of the right sternocleidomastoid muscle, and carotid artery injury. He was hemodynamically stable and there was no neurological deficit. Arteriogram of the neck disclosed a pseudoaneurysm with an arteriovenous fistula between the common carotid artery and internal jugular vein. At surgery, the tears in the carotid artery and jugular vein were sutured and a vacuum drain was introduced. The postoperative course was uneventful, and the patient was discharged 5 days later. Instead of the expected results of a penetrating carotid artery injury, such as blood loss, airway obstruction or neurological deficit, the arteriovenous fistula caused by the pellet actually saved the patient's life. Blood flow from the artery via the pseudoaneurysm to the jugular vein kept the patient in stable condition.

Adult↗
PubMed1997

Feasibility analysis of a case-based reasoning system for automated detection of coronary heart disease from myocardial scintigrams.

Myocardial perfusion scintigraphy is a noninvasive diagnostic method for the evaluation of patients with suspected or proven coronary artery disease (CAD). We utilized case-based reasoning (CBR) methods to develop the computer-based image interpretation system SCINA which automatically derives from a scintigraphic image data set an assessment concerning the presence of CAD. We compiled a case library of 100 patients who underwent both perfusion scintigraphy and coronary angiography to document or exclude the presence of CAD. The angiographic diagnosis of the retrieved nearest neighbor match of a scintigraphic input case was selected as the CBR diagnosis. We examined the effects of input data granularity, case indexing, similarity metric, and adaptation on the diagnostic accuracy of the CBR application SCINA. For the final prototype, sensitivity and specificity for detection of coronary heart disease were 98% and 70% suggesting that CBR systems may achieve a diagnostic accuracy that appears feasible for clinical use.

Adaptation, Physiological↗
PubMed1997

Human stanniocalcin inhibits renal phosphate excretion in the rat.

Stanniocalcin (STC) is a glycoprotein hormone first identified in bony fishes where it counteracts hypercalcemia by inhibiting gill calcium uptake and stimulating renal inorganic phosphate (Pi) reabsorption. Human STC (hSTC) has recently been cloned and sequenced and is highly homologous to the fish hormone at the amino acid level. The objective of this study was to examine the possible effects of hSTC on electrolyte homeostasis and renal function in the rat. Recombinant hSTC was expressed in bacteria and purified by metal-ion affinity chromatography and reverse-phase high performance liquid chromatography. Anesthetized animals were given bolus infusions of 1, 5, or 10 nmol hSTC per kilogram of body weight. Control animals received solvent alone. The most effective dosage was 5 nmol/kg, which caused significant reductions in both absolute and fractional phosphate excretion in comparison with control rats. The hSTC had no effect on the renal excretion of other ions, the glomerular filtration rate, renal blood flow, blood pressure, or plasma electrolytes (Na+, K+, Ca2+, Pi, Mg/+). The maximum effect of hSTC on phosphate excretion was observed 60-80 minutes postinjection. Lesser effects were obtained with higher and lower dosages of hormone. When renal cortical brush-border membrane vesicles were isolated from control and hormone-treated animals 80 minutes postinjection, the rate of Na+/Pi cotransport was found to be 40% higher in vesicles from hormone-treated animals (p < 0.01; 5 nmol hSTC/kg). Together, the renal clearance and membrane vesicle data indicate that hSTC participates in the renal regulation of Pi homeostasis in mammals.

Animals↗
PubMed1997

Nonlethal gamma radiation displays similar cytoplasmic rearrangements as 12(S)-HETE.

Timar et al. (Int. J. Canc., 52:594-603, 1992) and Onoda et al. (Rad. Res., 130:281-288, 1992) implicated 12(S)-HETE and nonlethal gamma radiation respectively, in enhanced expression of the alpha IIb beta 3 integrin receptor in B16a tumor cells. 12(S)-HETE has been reported to induce rearrangement of cytoplasmic elements and movement of cytoplasm (Haddad and Taylor, Proc. Amer. Cancer Res., 34:51, 1993); Timar et al., Cell Motil. Cytoskel., 26:49-65, 1993). Here, we report similar results in B16a tumor cells by post 90 cGy gamma radiation. Control cells were circular without cytoplasmic processes with the majority of their organelles and elements in perinuclear regions both surrounded by a ring of actin microfilaments. The cell's extensive leading edge was organelle free with the exception of occasional endoplasmic reticular cisternae parallel to one or two microtubules, and short bundles of actin microfilaments perpendicular to the plasma membrane. As early as 5 sec, but better defined by 60-90 sec, one end of elongated microfilaments bundles became associated with the plasma membrane while the other end of the bundles became associated with perinuclear mass protrusions. By 5 min, prominent by 15 min, protrusions, now separated from the leading edge by mixture of bundle and ring microfilaments, reached the plasma membrane to form cellular processes. By 30 min, some cytoplasmic masses showed signs of retraction along with the disappearance of their associated mixed microfilaments. As well as numerous vesicles of unknown origin, primarily associated with microtubules perpendicular to the plasma membrane, mitochondria and endoplasmic reticular cisternae were found in the cytoplasmic masses.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1996

Immunocytochemical localization of stanniocalcin cells in the rat kidney.

Stanniocalcin (STC) is a polypeptide hormone that was first discovered in fishes, where it functions as a regulator of calcium and phosphate homoeostasis. Recently, complementary DNAs encoding human STC (hSTC) have been characterized, and recombinant hSTC has been synthesized in a bacterial expression system. In preliminary studies, STC-immunoreactive cells have already been identified in human kidney tubules with antibodies to recombinant hSTC. The purpose of this study was to map the overall spatial distribution of STC cells in mammalian kidney, using the rat as a model system. Immunocytochemistry was performed on fixed sections of rat kidney tissue using hSTC antiserum in conjunction with fluorescein isothiocyanate-conjugated second antibodies. STC-immunoreactive cells were found in cortical thick ascending limb, in macula densa, in distal convoluted tubules, and in the cortical and medullary collecting ducts. All cortical thick ascending limb cells contained immunoreactive STC. Most distal convoluted tubules cells contained STC, and these were identified as principal cells. The distribution of STC cells in cortical and medullary collecting ducts also corresponded closely to the known frequently of principle cells in these segments, suggesting that principal cells are the site of STC storage and/or synthesis in both distal convoluted tubules and collecting ducts. Some collecting duct intercalated cells contained STC as well, and these were tentatively identified as alpha-type intercalated cells. As all tubular segments containing STC are known to be involved in regulated ion transport, renally derived STC may be acting in an autocrine, paracrine and/or endocrine fashion to regulate one or more of these transport processes.

Animals↗
PubMed1996

Development of a standardized proforma for reporting computerized tomographic images of the paranasal sinuses.

The complex regional anatomy of the paranasal sinuses has only recently been elucidated through the use of modern imaging techniques. The advent of computerized tomography in the delineation of sinonasal pathology and anatomic variation has proven invaluable to the otolaryngologist in preoperative planning for functional endoscopic sinus surgery (FESS). Frequently, the radiologic reporting schemes for these studies are not standardized, and in many respects have been found to be inadequate. This study attempts to develop a simple reporting proforma that the head and neck radiologist can routinely use in order to facilitate the presentation of CT scan findings in evaluating sinus, nasal, or upper airway pathology. Over 100 CT sinus reports that had previously been reported were re-read according to this reporting scheme and were analyzed in order to determine whether any significant discrepancies existed. These differences were then classified according to their incidental, minor, and major surgical significance. It is hoped that through the development of a standardized proforma, the complementary relationship between preoperative imaging and endoscopic intervention can be consolidated and further enhanced.

Adolescent↗
PubMed1996

"Veno-Press"--a new sequential intermittent pneumatic device for the prevention of perioperative deep vein thrombosis.

The prevention of peri-operative deep vein thrombosis (DVT) and the potentially hazardous pulmonary embolism that may follow is still a major medical issue. Intermittent pneumatic compression is one of the many methods currently in use for this purpose. No information is available, however, regarding the venous flow alterations that occur during employment of a pneumatic compression device under general anesthesia. The aim of this study is to delineate these venous flow variations and to determine the optimal pump setting for the prevention of operative venous stasis and its sequelae, postoperative DVT. A new sequential intermittent pneumatic device, the "Veno-Press", was applied on 20 volunteers of whom 10 were undergoing surgery unrelated to the lower limbs, during the pre-anesthesia and during general anesthesia. The venous velocity patterns over the femoral vein were depicted via duplex scanning under different pressure and rhythm settings of the device. The "Veno-Press" induced a marked augmentation in venous blood velocity flow. A further 10-30% augmentation was noted when the patients were under general anesthesia, as well as a 10-30% increase in the femoral vein diameter. None of the patients developed postoperative DVT. This device is a very efficient tool for augmentation of venous blood velocity, especially during general anesthesia. Its effectiveness is most probably the result of the compressive action over the relaxed--and hence enlarged--capacitant veins of the anesthetized patient. We suggest that the "Veno-Press", if properly timed, is very efficient in venostasis prevention, leading presumably to a decline in the occurrence of DVT and pulmonary embolisms in the surgical patient.

Anesthesia, General↗
PubMed1996

[Screening of Streptococcus agalactiae (group B) in the perinatal period].

OBJECTIVE: To determine the carriage rate of Streptococcus agalactiae in a group of pregnant women and evaluate its role in a neonatal infections. DESIGN: Prospective study between December 1992 and May 1993. SETTING: University hospital. PARTICIPANTS: 166 patients aged 17 to 41 years (m = 28 yrs) with a gestational age of 32 to 42 wks (m = 39.99 +/- 1.73) were admitted to the delivery suite. All patients had a vaginal swab on admission before any lavage. RESULTS: The recovery rate of Streptococcus agalactiae (group B) was found to be 7.8% (13/166) in our population. Twelve of the thirteen newborn to colonized mothers (92%) were term newborn as compared to 141 of 153 (92.1%) newborn to non-colonized mothers (p = 0.72). Three of thirteen (23%) colonized mothers had premature rupture of membranes and 23% (3/13) had prolonged labor > 12 h as compared to of 38 (25.1%) and 8 (5.1%) non-colonized mothers (respectively p = 0.58; NS; p = 0.035). No intra-partum fever was reported. All neonates born to colonized mothers had a birth weight > 2,800 g, an average Apgar score of 8.6 while neonates of non-colonized women had a weight > 2,800 g in 89.4% of cases and an average Apgar of 8.8 (p = 0.9). Two (15.4%) newborn infants born to colonized mothers had an early neonatal infection: one had a pneumonia and had a favorable outcome, the other one developed sepsis and meningitis and died on day 3. CONCLUSION: Despite the low rate of Streptococcus agalactiae (group B) colonization (found in our population), regular identification of the organism is recommended because of the high risk of neonatal infection with a high mortality. Further studies on a larger group are needed to confirm such an approach.

Adolescent↗
PubMed1995

Anterior spinal artery syndrome. Paraplegia following segmental ischaemic injury to the spinal cord after oesophagectomy.

A case of unexpected paraplegia after oesophageal resection under general anaesthesia combined with epidural analgesia and intra-operative intercostal block is described. Patients with compromised cardiovascular and respiratory function undergoing thoracic or major abdominal surgery can benefit significantly intra-operatively from a combination of general anaesthesia and regional analgesia. The continued use of regional analgesia into the postoperative period offers even more advantages. General anaesthesia administered before regional analgesia may, however, mask complications related to the regional technique and delay the instigation of corrective measures. The blood supply to the anterior part of the spinal cord, through the artery of Adamkiewicz, may be impaired intra-operatively leading to neurological sequelae known as the anterior spinal artery syndrome, characterised by loss of motor function with intact or partially intact sensory function. Patients at risk of developing the syndrome can be identified pre-operatively.

Aged↗
PubMed1995

Immunomorphological characterization and effects of 12-(S)-HETE on a dynamic intracellular pool of the alpha IIb beta 3-integrin in melanoma cells.

In metastatic B16a murine melanoma cells, alpha IIb beta 3 integrin was shown to be one of the key adhesion molecules responsible for matrix adhesion and spreading. Upon stimulation, alpha IIb beta 3 can be upregulated at the cell surface due to translocation of the receptor to the plasma membrane from an intracellular pool. Here we have characterized this integrin pool as a tubulovesicular structure (TVS) corresponding to endosomes. TVS was found to be associated temporarily with microtubules and intermediate filaments especially after protein kinase C (PKC) stimulation with a lipoxygenase metabolite of arachidonic acid, 12-(S)-hydroxyeicosatetraenoic acid [12-(S)-HETE]. After PKC stimulation, the predominantly vesicular TVS became elongated and alpha IIb beta 3 appeared at the apical plasma membrane and microvilli. Disruption of either the microtubules or intermediate filaments prevented the 12-(S)-HETE effect both on vesicular to tubular transition of TVS as well as on surface expression of this integrin. The connection with the Golgi system of the integrin-containing TVS was proved by a Golgi-inhibitor (brefeldin A) pretreatment, which prevented the PKC-stimulation-induced TVS elongation and subsequent receptor-upregulation at the cell surface. After a soluble ligand binding (mAb to the alpha IIb beta 3 complex) the surface receptor endocytosed back to the TVS indicating the presence of a dynamic, cytoskeleton associated integrin pool in melanoma cells.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗